How do you calculate your future effective tax rate?
Pretty deep into FIRE planning. The thing that I'm not clear on is how I can accurately calculate my future effective tax rate.
I have an estimated after tax budget and I have a target magi I want to stay under (but unsure if I'll be able to get under it). I'm not too clear on the cost basis of my taxable brokerage. When the time comes, I assume i'll withdraw from my taxable account first until I reach my target magi, then use cash and my Roth contributions to make up the gap.
All this to say, it seems hard to nail down the tax rate as there are many variables such as whether we can stay under a certain magi for ACA subsidies, cost basis of taxable brokerage when we sell etc.
Is there a simple way to get a good-enough estimate of future effective rate so I can figure out my true budget? I'm curious what others are doing.